**3. Biopesticides**

The need for biopesticides has been increased significantly in recent years, particularly in developing countries, due to restrictions placed on the use of some synthetic pesticides, such as organophthaloids, organochlorines, carbamates, and organophosphates, among other things. Synthetic pesticides are not only harmful to pests and diseases at the time of application, but they also have the potential to contaminate plant crops, posing a threat to human health, animal welfare, and environmental health. Synthetic pesticides are used to control pests and diseases in agriculture. In agriculture, synthetic pesticides are used to manage pests and illnesses that are introduced via the soil. As reported by the Environmental Protection Agency, synthetic pesticides are also harmful to both people and animals. They are also bad for the health of the ecosystem. When it comes to biochemistry, chemical pesticides are characterized by alterations in the signaling system, inhibition of enzymes, pH shifts, disruption of electrolytic balance, osmotic and membrane breakdown, pH gradients across membranes, and other characteristics. They also generate free radicals and other toxic compounds, which have the potential to damage proteins and DNA, as well as cause tissue degeneration, among other undesirable effects [14]. A wide range of diseases has been linked to the use of synthetic pesticides, including Parkinson's disease and neurotoxicity, type 2 diabetes, endocrine disruption, many cancers, and obesity, among others. Parkinson's disease is the most well-known of these disorders. It has been shown that the use of synthetic pesticides is linked with the development of these diseases, which may be due in part to the mechanisms of action of these chemicals, as well as the increasing exposure of individuals to these chemicals over time [33–35]. Despite the fact that it is regrettable, the majority of pesticides now in use are being phased out at a rapid rate, which is a good trend in the industry. On the other hand, pesticides that are still in use continue to accumulate in the human body with every meal that is eaten. In addition, employees who have been exposed to pesticides have been observed to get drunk as a result of the pesticides they have been exposed to over the course of their shift [36]. Natural pesticides offer many benefits over synthetic pesticides, the most significant of which is that they are less harmful to the environment and human health. However, this does not mean that they should be utilized recklessly or without consideration for the repercussions of their actions. Even if certain products have been authorized for use as biopesticides, it is conceivable that they may cause health issues among members of the general population. Large quantities of copper, which is an essential nutrient in the diets of both mammals and plants, have the potential to be poisonous to both humans and animals and hazardous to aquatic life if eaten over an extended period of time. There is also concern about toxic plant species, microalgae, and algae such as *Microcystis aeruginosa*, *Chrysanthemum* spp., *Gracilaria coronopifolia*, and others that are harmful because their appearance may be similar to that of hazardous compounds such as cyanide, among other things, and they are difficult to identify [13, 14].

As the name implies, biopesticides are pesticides that include active ingredients formed by microorganisms or natural materials rather than synthetic chemicals. They are used to control insects in a variety of circumstances and are referred to as "biopesticides." Pesticides derived from plants are divided into three categories: (a) microbial biopesticides, which are microorganisms that are effective against diseases and insects; (b) botanical biopesticides; and (c) plant-incorporated protectants. Microbial biopesticides are microorganisms that are effective against diseases and insects. Microbial biopesticides are microorganisms that have been shown to be efficient against many illnesses and insects in the field. A microbial biopesticide is a bacterium that is effective against a wide range of diseases and insect species, including fungi [10].

#### **3.1 Microbial biopesticides**

The presence of fungus is associated with insect damage. *Metarhizium anisopliae* and *Beauveria bassiana* are two forms of entomopathogenic fungi that may be found in the environment and are both harmful to insects. According to the World Health Organization, as soon as *B. bassiana* spores come into contact with the body of an insect host, they begin to develop, penetrate the cuticle, and multiply within the insect host, eventually killing the insect host and spreading to other insects in the surrounding area. *B. bassiana* is a fungus that can cause death in insects. As the body ages, it produces a white mold that spreads new spores into the surrounding environment, leading the environment to become more contaminated as a result of the pollution. A host insect becomes infected when the spores of the fungus *M. anisopliae* come into touch with the insect's body, causing the spores to sprout and the hyphae that emerge to pierce the insect's cuticle, causing the insect to succumb to the infection. It then begins to spread throughout the insect's body, resulting in the insect being infected within a few days after first becoming exposed to the fungus. In order to prevent the development of soilborne diseases, microorganisms such as *Pseudomonas* and *Trichoderma* have been extensively employed as biopesticides for many years, and they are still being utilized in this capacity today [37]. According to the University of California, Berkeley, a filamentous fungus such as *Trichoderma* may be found growing on organic materials such as rotting wood, soil and other organic materials. Many Trichoderma species, including *T. virens, T. viride*, and *T. harzianum*, have been found to have strong biocontrol capability. Many other competing methods for resources have been discovered to have biocontrol potential, including mycoparasitism, which is caused by the release of cell wall-degrading enzymes such as proteases, chitinases, and glucanases, among other things. The antibiotic compounds heptelidic acid and harzianic acid, as well as alamethicins, glisoprenins, tricholin and antibiotics, 6-pentylpyrone, peptaibols, viridin, and massoilactone, can all cause antibiosis. Heptelidic acid and harzianic acid are two of the most commonly encountered antibiotic compounds. Infections caused by bacteria are treated using the antibiotic heptelidic acid, which is produced by bacteria and used to treat infections caused by other bacteria [38].

*Trichoderma* is effective against a wide range of pathogenic fungi, including *Candida albicans*, *Phytophagthora*, *Fusarium*, *Sclerotia*, and other pathogenic fungi, in addition to *Candida albicans*. Cotton crops are affected by *Fusarium* wilt disease, caused by the fungus *Fusarium* sp., while other crops, such as maize, are affected by *Rhizoctonia* sp. and *Pythium* sp. As a consequence of using this technique, the development of cucumber resistance to the anthracnose disease caused by the fungus *Colletotrichum* sp. was aided. *Pseudomonas aeruginosa* weakened infections are characterized by the release of various derivatives and antibiotics such as pyoluteorin (Plt), 2,4-diacetylaminoglucinol (DAPG), phenazine-1-pyrrolnitrin (Prn),

*Nano-Biopesticides as an Emerging Technology for Pest Management DOI: http://dx.doi.org/10.5772/intechopen.101285*

carboxylic acid (PCA), or the development of systemic resistance (ISR) [39]. When it comes to developing microbial biopesticide formulations, microorganisms such as algae, bacteria, and fungus must be incorporated if the usage of these pesticides is to become more generally accepted. According to the International Biopesticide Trade Association, the biopesticide industry is experiencing an outbreak of bacteria, particularly among *Bacillus thuringiensis* species, which are commonly used to control insect infestations in plantations and are now being transported across multiple countries [40]. Whenever parasites eat this bacterium, it creates a toxic endotoxin that attaches itself to the stomach of the insect and causes holes to develop, resulting in anion imbalances in the insect's body, insensitivity of the insect's digestive system, and eventually, the insect's death. According to industry standards, these pesticides are usually regarded as less toxic to birds, mammals, and non-target insects than conventional insecticides, and as a result, they are believed to be less damaging to the environment. Microalgae as biopesticides, despite this, have been proven to be helpful in the prevention and control of the spread of a wide variety of plant-borne diseases. Many studies have demonstrated this bacterium's ability to produce a diverse range of bio-compounds, including terpenes and growth regulators, as well as phenolic chemicals and other molecules. These studies have all demonstrated this bacterium's ability to produce these compounds, as well as its potential to produce other molecules. Terpenes, growth regulators, phenolic compounds, and other molecules are among the substances studied [41, 42].

#### **3.2 Biochemical biopesticides**

Non-toxic biochemical pesticides are natural insecticides produced by animals, plants, and insects. They do not damage the creatures that produce them. They are employed to manage pests without killing them. These chemicals may assist in growth and development by attracting or repelling pests (pheromones) and acting as plant growth regulators (PGR). It's difficult to tell whether a biopesticide is hazardous since so few countries have committees to test metabolites.

As a consequence, evaluating a biopesticide's safety is difficult [43]. Since their discovery, Auxin-type PGRs have been hailed as one of the most effective herbicides and biological control agents on the market. And for a good reason. It is generally recognized as one of the most efficient herbicides and biological control agents on the market today. Consider the difference in action selectivity between marijuana and PGR. Marijuana has a more selective effect, perhaps due to its fast detoxification process. Low concentrations of these chemicals promote cell elongation, biofertilizer activity, cell division, and cell growth. Dense doses cause weeds to get intoxicated and exhibit developmental abnormalities such as impaired respiration, carbon absorption, and transpiration. In the end, these anomalies harm weeds' circulatory systems and membranes, leading to their demise [14].

#### **3.3 Botanical biopesticides**

When applied to crops, pesticides (chemical compounds and plant extracts) are used to prevent the growth of pests (including insects) of various types. Pesticides are used to limit, halt, or otherwise manage pests of many kinds, including insects. Some ways in which plant security may be achieved include the utilization of a variety of secondary metabolites produced from plant sources such as essential oils, phenolics, and terpenes, among other things [44]. The non-persistency of essential oils in the environment, along with the fact that they are non-toxic to animals, has led to their being widely regarded as one of the most efficient agricultural pesticides presently available. As acaricides and insecticides, these compounds have the

potential to be utilized in the environment, where they may also be used to inhibit the growth of fungus and bacteria. When essential oils are applied to plant cultures, the anti-oxidant properties of the oils protect the plants from pro-oxidants found in proteins and DNA, which cause cytotoxicity, the formation of reactive oxygen species, as well as the breakdown of cell membranes and organelles in the microorganisms that infect the plants [45]. However, the effectiveness of a biological pesticide can be affected by several factors, including the mist of the substance harvested, the method of extraction used to obtain this type of biopesticide, and the age of the plant from which the oil will be collected. The toxicity of a biological pesticide can also be affected by several factors, including the phenological age of the plant from which the oil will be collected. Although agricultural pesticides have many advantages, their use has been restricted for a variety of reasons, including their inability to maintain stability over time, the complexity of the extracted combination, extraction techniques, or formulation of the active component, as well as difficulties encountered during the purification process [46].

There are a number of plants that have been recognized as intrinsic sources of agricultural pesticides, as described in **Table 1**. The pests that are targeted by the insecticides contained in those plants are also included in the table. The ethanolic plant extracts of ginger (*Zingiber officinale*), turmeric *(Curcuma longa*), pepper (*Capsicum frutescens*), lemon (*Citrus limon*), and garlic (*Allium sativum*) have been shown to significantly inhibit the growth of *Fusarium oxysporum* sp., *Alternaria* 



#### *Nano-Biopesticides as an Emerging Technology for Pest Management DOI: http://dx.doi.org/10.5772/intechopen.101285*

#### **Table 1.**

*The potential plant compounds as botanical pesticides and respective target pests.*

*solani*, *Rhizoctonia solani*, *Pythium ultimum*, and *Lycopersicium* sp. [64]. Regarding growth inhibition, turmeric (*Curcuma longa)* has been shown to be the most effective herb, with results against *Alternaria solani* reaching up to 73 percent effectiveness. *In vitro* studies have demonstrated that the herbs *Rosmarinus officinalis, Rhus coriaria*, and *Eucalyptus globulus*, among others, effectively inhibit the development of the pathogen *Pseudomonas syringae* tomato [65]. A study conducted in a greenhouse showed that the *Eucalyptus globulus* tree was very efficient in reducing the bacterial specks of tomato (*Pseudominas syringae* p.v. tomato) to a degree of as much as 65% when cultivated in a greenhouse. In one research, when juvenile root-knot nematodes (*Meloidogyne* sp.) were exposed to extracts of the *Nerium oleander* at a 5 percent concentration and the extracts were applied topically, the mortality of the worms increased. When treated with extracts of *A. sativum*, *Eucalyptus* sp., *Azadiractha indica*, *Cinnamomum versicolor*, *Zingiber officinale*, and *Nerium oleander* at a concentration of 10 percent, the mortality rate of insects on second-stage juveniles ranges between 65 and 100 percent, and when treated with a concentration of 20 percent, the mortality rate ranges between 65 and 100 percent [66].
